Shares of Citigroup (C) are trading down over 3% in the pre-market after CEO Vikram Pandit announced his resignation effective immediately. The chart below shows the performance of Citigroup's (C) stock under Pandit. On a reverse split adjusted basis, the stock dropped nearly 90%. Granted, the stock was in a free-fall when he stepped in, but all in all, Pandit's experience at Citigroup was probably not what he envisioned when he first stepped in.